Fungi moulds mushrooms yeasts
Fungi can be single celled or very complex multicellular organisms. They are found in just about any habitat but most live on the land, mainly in soil or on plant material rather than in sea or fresh water. A group called the decomposers grow in the soil or on dead plant matter where they play an important role in the cycling of carbon and other elements. Some are parasites of plants causing diseases such as mildews, rusts, scabs or canker. In crops fungal diseases can lead to significant monetary loss for the farmer. A very small number of fungi cause diseases in animals. In humans these include skin diseases such as athletes’ foot, ringworm and thrush.
The three major groups of fungi are:
-multicellular filamentous moulds
-macroscopic filamentous fungi that form large fruiting bodies. Sometimes the group is referred to as ‘mushrooms’, but the mushroom is just the part of the fungus we see above ground which is also known as the fruiting body.
-single celled microscopic yeasts
Many fungi have important symbiotic relationships with organisms from most if not all Kingdoms.These interactions can be mutualistic or antagonistic in nature, or in the case of commensal fungi are of no apparent benefit or detriment to the host.
With plants
Mycorrhizal symbiosis between plants and fungi is one of the most well-known plant–fungus associations and is of significant importance for plant growth and persistence in many ecosystems; over 90% of all plant species engage in mycorrhizal relationships with fungi and are dependent upon this relationship for survival.[148]
A microscopic view of blue-stained cells, some with dark wavy lines in them
The dark filaments are hyphae of the endophytic fungus Neotyphodium coenophialum in the intercellular spaces of tall fescue leaf sheath tissue
The mycorrhizal symbiosis is ancient, dating to at least 400 million years ago.[129] It often increases the plant's uptake of inorganic compounds, such as nitrate and phosphate from soils having low concentrations of these key plant nutrients.[140][149] The fungal partners may also mediate plant-to-plant transfer of carbohydrates and other nutrients. Such mycorrhizal communities are called "common mycorrhizal networks".[150] A special case of mycorrhiza is myco-heterotrophy, whereby the plant parasitizes the fungus, obtaining all of its nutrients from its fungal symbiont.[151] Some fungal species inhabit the tissues inside roots, stems, and leaves, in which case they are called endophytes.[152] Similar to mycorrhiza, endophytic colonization by fungi may benefit both symbionts; for example, endophytes of grasses impart to their host increased resistance to herbivores and other environmental stresses and receive food and shelter from the plant in return.[153]
With algae and cyanobacteria
A green, leaf-like structure attached to a tree, with a pattern of ridges and depression on the bottom surface
The lichen Lobaria pulmonaria, a symbiosis of fungal, algal, and cyanobacterial species
Lichens are formed by a symbiotic relationship between algae or cyanobacteria (referred to in lichen terminology as "photobionts") and fungi (mostly various species of ascomycetes and a few basidiomycetes), in which individual photobiont cells are embedded in a tissue formed by the fungus.[154] Lichens occur in every ecosystem on all continents, play a key role in soil formation and the initiation of biological succession,[155] and are the dominating life forms in extreme environments, including polar, alpine, and semiarid desert regions.[156] They are able to grow on inhospitable surfaces, including bare soil, rocks, tree bark, wood, shells, barnacles and leaves.[157] As in mycorrhizas, the photobiont provides sugars and other carbohydrates via photosynthesis, while the fungus provides minerals and water. The functions of both symbiotic organisms are so closely intertwined that they function almost as a single organism; in most cases the resulting organism differs greatly from the individual components. Lichenization is a common mode of nutrition; around 20% of fungi—between 17,500 and 20,000 described species—are lichenized.[158] Characteristics common to most lichens include obtaining organic carbon by photosynthesis, slow growth, small size, long life, long-lasting (seasonal) vegetative reproductive structures, mineral nutrition obtained largely from airborne sources, and greater tolerance of desiccation than most other photosynthetic organisms in the same habitat.[159]
With insects
Many insects also engage in mutualistic relationships with fungi. Several groups of ants cultivate fungi in the order Agaricales as their primary food source, while ambrosia beetles cultivate various species of fungi in the bark of trees that they infest.[160] Likewise, females of several wood wasp species (genus Sirex) inject their eggs together with spores of the wood-rotting fungus Amylostereum areolatum into the sapwood of pine trees; the growth of the fungus provides ideal nutritional conditions for the development of the wasp larvae.[161] Termites on the African savannah are also known to cultivate fungi,[142] and yeasts of the genera Candida and Lachancea inhabit the gut of a wide range of insects, including neuropterans, beetles, and cockroaches; it is not known whether these fungi benefit their hosts.[162] The larvae of many families of fungicolous flies, particularly those within the superfamily Sciaroidea such as the Mycetophilidae and some Keroplatidae feed on fungal fruiting bodies and sterile mycorrhizae.[163]
As pathogens and parasites
A thin brown stick positioned horizontally with roughly two dozen clustered orange-red leaves originating from a single point in the middle of the stick. These orange leaves are three to four times larger than the few other green leaves growing out of the stick, and are covered on the lower leaf surface with hundreds of tiny bumps. The background shows the green leaves and branches of neighboring shrubs.
The plant pathogen Aecidium magellanicum causes calafate rust, seen here on a Berberis shrub in Chile.
Many fungi are parasites on plants, animals (including humans), and other fungi. Serious pathogens of many cultivated plants causing extensive damage and losses to agriculture and forestry include the rice blast fungus Magnaporthe oryzae,[164] tree pathogens such as Ophiostoma ulmi and Ophiostoma novo-ulmi causing Dutch elm disease,[165] and Cryphonectria parasitica responsible for chestnut blight,[166] and plant pathogens in the genera Fusarium, Ustilago, Alternaria, and Cochliobolus.[146] Some carnivorous fungi, like Paecilomyces lilacinus, are predators of nematodes, which they capture using an array of specialized structures such as constricting rings or adhesive nets.[167]
Some fungi can cause serious diseases in humans, several of which may be fatal if untreated. These include aspergilloses, candidoses, coccidioidomycosis, cryptococcosis, histoplasmosis, mycetomas, and paracoccidioidomycosis. Furthermore, persons with immuno-deficiencies are particularly susceptible to disease by genera such as Aspergillus, Candida, Cryptoccocus,[147][168][169] Histoplasma,[170] and Pneumocystis.[171] Other fungi can attack eyes, nails, hair, and especially skin, the so-called dermatophytic and keratinophilic fungi, and cause local infections such as ringworm and athlete's foot.[172] Fungal spores are also a cause of allergies, and fungi from different taxonomic groups can evoke allergic reactions.
Ustilago maydis is a pathogenic plant fungus that causes smut disease in maize and teosinte. Plants have evolved efficient defense systems against pathogenic microbes such as U. maydis. A rapid defense reaction after pathogen attack is the oxidative burst where the plant produces reactive oxygen species at the site of the attempted invasion. U. maydis can respond to the oxidative burst with an oxidative stress response, regulated by the gene YAP1. The response protects U. maydis from the host defense, and is necessary for the pathogen’s virulence.[178] Furthermore, U. maydis has a well-established recombinational DNA repair system which acts during mitosis and meiosis.[179] The system may assist the pathogen in surviving DNA damage arising from the host plant’s oxidative defensive response to infection.[180]
Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. C. neoformans usually infects the lungs, where it is phagocytosed by alveolar macrophages.[181] Some C. neoformans can survive inside macrophage, which appears to be the basis for latency, disseminated disease, and resistance to antifungal agents. One mechanism by which C. neoformans survives the hostile macrophage environment is by up-regulating the expression of genes involved in the oxidative stress response.[181] Another mechanism involves meiosis. The majority of C. neoformans are mating "type a". Filaments of mating "type an" ordinarily have haploid nuclei, but they can become diploid (perhaps by endoduplication or by stimulated nuclear fusion) to form blastospores. The diploid nuclei of blastospores can undergo meiosis, including recombination, to form haploid basidiospores that can be dispersed.[182] This process is referred to as monokaryotic fruiting. this process requires a gene called DMC1, which is a conserved homologue of genes recA in bacteria and RAD51 in eukaryotes, that mediates homologous chromosome pairing during meiosis and repair of DNA double-strand breaks. Thus, C. neoformans can undergo a meiosis, monokaryotic fruiting, that promotes recombinational repair in the oxidative, DNA damaging environment of the host macrophage, and the repair capability may contribute to its virulence.
source : http://en.wikipedia.org/wiki/Fungus and http://www.microbiologyonline.org.uk/about-microbiology/introducing-microbes/fungi
The three major groups of fungi are:
-multicellular filamentous moulds
-macroscopic filamentous fungi that form large fruiting bodies. Sometimes the group is referred to as ‘mushrooms’, but the mushroom is just the part of the fungus we see above ground which is also known as the fruiting body.
-single celled microscopic yeasts
Many fungi have important symbiotic relationships with organisms from most if not all Kingdoms.These interactions can be mutualistic or antagonistic in nature, or in the case of commensal fungi are of no apparent benefit or detriment to the host.
With plants
Mycorrhizal symbiosis between plants and fungi is one of the most well-known plant–fungus associations and is of significant importance for plant growth and persistence in many ecosystems; over 90% of all plant species engage in mycorrhizal relationships with fungi and are dependent upon this relationship for survival.[148]
A microscopic view of blue-stained cells, some with dark wavy lines in them
The dark filaments are hyphae of the endophytic fungus Neotyphodium coenophialum in the intercellular spaces of tall fescue leaf sheath tissue
The mycorrhizal symbiosis is ancient, dating to at least 400 million years ago.[129] It often increases the plant's uptake of inorganic compounds, such as nitrate and phosphate from soils having low concentrations of these key plant nutrients.[140][149] The fungal partners may also mediate plant-to-plant transfer of carbohydrates and other nutrients. Such mycorrhizal communities are called "common mycorrhizal networks".[150] A special case of mycorrhiza is myco-heterotrophy, whereby the plant parasitizes the fungus, obtaining all of its nutrients from its fungal symbiont.[151] Some fungal species inhabit the tissues inside roots, stems, and leaves, in which case they are called endophytes.[152] Similar to mycorrhiza, endophytic colonization by fungi may benefit both symbionts; for example, endophytes of grasses impart to their host increased resistance to herbivores and other environmental stresses and receive food and shelter from the plant in return.[153]
With algae and cyanobacteria
A green, leaf-like structure attached to a tree, with a pattern of ridges and depression on the bottom surface
The lichen Lobaria pulmonaria, a symbiosis of fungal, algal, and cyanobacterial species
Lichens are formed by a symbiotic relationship between algae or cyanobacteria (referred to in lichen terminology as "photobionts") and fungi (mostly various species of ascomycetes and a few basidiomycetes), in which individual photobiont cells are embedded in a tissue formed by the fungus.[154] Lichens occur in every ecosystem on all continents, play a key role in soil formation and the initiation of biological succession,[155] and are the dominating life forms in extreme environments, including polar, alpine, and semiarid desert regions.[156] They are able to grow on inhospitable surfaces, including bare soil, rocks, tree bark, wood, shells, barnacles and leaves.[157] As in mycorrhizas, the photobiont provides sugars and other carbohydrates via photosynthesis, while the fungus provides minerals and water. The functions of both symbiotic organisms are so closely intertwined that they function almost as a single organism; in most cases the resulting organism differs greatly from the individual components. Lichenization is a common mode of nutrition; around 20% of fungi—between 17,500 and 20,000 described species—are lichenized.[158] Characteristics common to most lichens include obtaining organic carbon by photosynthesis, slow growth, small size, long life, long-lasting (seasonal) vegetative reproductive structures, mineral nutrition obtained largely from airborne sources, and greater tolerance of desiccation than most other photosynthetic organisms in the same habitat.[159]
With insects
Many insects also engage in mutualistic relationships with fungi. Several groups of ants cultivate fungi in the order Agaricales as their primary food source, while ambrosia beetles cultivate various species of fungi in the bark of trees that they infest.[160] Likewise, females of several wood wasp species (genus Sirex) inject their eggs together with spores of the wood-rotting fungus Amylostereum areolatum into the sapwood of pine trees; the growth of the fungus provides ideal nutritional conditions for the development of the wasp larvae.[161] Termites on the African savannah are also known to cultivate fungi,[142] and yeasts of the genera Candida and Lachancea inhabit the gut of a wide range of insects, including neuropterans, beetles, and cockroaches; it is not known whether these fungi benefit their hosts.[162] The larvae of many families of fungicolous flies, particularly those within the superfamily Sciaroidea such as the Mycetophilidae and some Keroplatidae feed on fungal fruiting bodies and sterile mycorrhizae.[163]
As pathogens and parasitesA thin brown stick positioned horizontally with roughly two dozen clustered orange-red leaves originating from a single point in the middle of the stick. These orange leaves are three to four times larger than the few other green leaves growing out of the stick, and are covered on the lower leaf surface with hundreds of tiny bumps. The background shows the green leaves and branches of neighboring shrubs.
The plant pathogen Aecidium magellanicum causes calafate rust, seen here on a Berberis shrub in Chile.
Many fungi are parasites on plants, animals (including humans), and other fungi. Serious pathogens of many cultivated plants causing extensive damage and losses to agriculture and forestry include the rice blast fungus Magnaporthe oryzae,[164] tree pathogens such as Ophiostoma ulmi and Ophiostoma novo-ulmi causing Dutch elm disease,[165] and Cryphonectria parasitica responsible for chestnut blight,[166] and plant pathogens in the genera Fusarium, Ustilago, Alternaria, and Cochliobolus.[146] Some carnivorous fungi, like Paecilomyces lilacinus, are predators of nematodes, which they capture using an array of specialized structures such as constricting rings or adhesive nets.[167]
Some fungi can cause serious diseases in humans, several of which may be fatal if untreated. These include aspergilloses, candidoses, coccidioidomycosis, cryptococcosis, histoplasmosis, mycetomas, and paracoccidioidomycosis. Furthermore, persons with immuno-deficiencies are particularly susceptible to disease by genera such as Aspergillus, Candida, Cryptoccocus,[147][168][169] Histoplasma,[170] and Pneumocystis.[171] Other fungi can attack eyes, nails, hair, and especially skin, the so-called dermatophytic and keratinophilic fungi, and cause local infections such as ringworm and athlete's foot.[172] Fungal spores are also a cause of allergies, and fungi from different taxonomic groups can evoke allergic reactions.
Ustilago maydis is a pathogenic plant fungus that causes smut disease in maize and teosinte. Plants have evolved efficient defense systems against pathogenic microbes such as U. maydis. A rapid defense reaction after pathogen attack is the oxidative burst where the plant produces reactive oxygen species at the site of the attempted invasion. U. maydis can respond to the oxidative burst with an oxidative stress response, regulated by the gene YAP1. The response protects U. maydis from the host defense, and is necessary for the pathogen’s virulence.[178] Furthermore, U. maydis has a well-established recombinational DNA repair system which acts during mitosis and meiosis.[179] The system may assist the pathogen in surviving DNA damage arising from the host plant’s oxidative defensive response to infection.[180]
Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. C. neoformans usually infects the lungs, where it is phagocytosed by alveolar macrophages.[181] Some C. neoformans can survive inside macrophage, which appears to be the basis for latency, disseminated disease, and resistance to antifungal agents. One mechanism by which C. neoformans survives the hostile macrophage environment is by up-regulating the expression of genes involved in the oxidative stress response.[181] Another mechanism involves meiosis. The majority of C. neoformans are mating "type a". Filaments of mating "type an" ordinarily have haploid nuclei, but they can become diploid (perhaps by endoduplication or by stimulated nuclear fusion) to form blastospores. The diploid nuclei of blastospores can undergo meiosis, including recombination, to form haploid basidiospores that can be dispersed.[182] This process is referred to as monokaryotic fruiting. this process requires a gene called DMC1, which is a conserved homologue of genes recA in bacteria and RAD51 in eukaryotes, that mediates homologous chromosome pairing during meiosis and repair of DNA double-strand breaks. Thus, C. neoformans can undergo a meiosis, monokaryotic fruiting, that promotes recombinational repair in the oxidative, DNA damaging environment of the host macrophage, and the repair capability may contribute to its virulence.
source : http://en.wikipedia.org/wiki/Fungus and http://www.microbiologyonline.org.uk/about-microbiology/introducing-microbes/fungi